VRTX Tower Enclosure - PCIe power adapters

I have the VRTX Tower Enclosure (HBF48M2). I am trying to add 2 x nVidia Quadro RTX 4000 GPU's. The enclosure appears to have 3 x 6-pin female power connectors at each PCIe slot. My GPU's have 8-pin connectors. I need the cables required to connect the 2 GPU's please. The power should be plenty as I have the 1600w supplies. My understanding is the 2 extra on the GPU's are sensory/confirmation pins for the unit to draw 150w instead of the standard 75w.

Thanks in advance.